This invention relates to a projection image system and an assembling system therefor, and more particularly to a projection image system wherein a large screen is formed by piling in matrix a plurality of projection image units in vertical and horizontal directions and an assembly system for assembling such a projection image system.
Generally, projection image systems are roughly classified into two types, one being for home use and the other being for business use. In case of projection image systems for business use, the systems are often used as display systems in theaters or outdoors, and in this type of projection image systems, a large screen is formed by piling in matrix a plurality of projection image units as shown in FIG. 25.
FIG. 26 shows an example of a conventional projection image unit A. As shown in FIG. 26, the projection image unit A has a casing 1 having a box-like form, and a screen 2 is mounted on one end face thereof. This screen 2 consists of two lenses, one being a Fresnel lens arranged on an inner surface of the casing 1 and the other being lenticular lens. Inside from the screen 2 at a rear end thereof is incorporated a color projector, not shown, to project images on the screen 2. On the side face of the casing 1 is arranged a handle 3 for convenience of transportation, transfer and installation thereof, and on the top face of the casing 1 are arranged rings 4 for hanging the casing 1 for the same purposes as described above. A connecting fitting 5 is used to connect a projection image unit A to other projection image unit A adjoining in the horizontal direction when arranged in matrix as a pair with a step 6 arranged at the other edge of the casing 1. In brief, the connecting fitting 5 engages with the step 6 of the adjoining projection image unit A, thus projection image units A being connected with each other in the horizontal direction. The casing 1 has a top surface position in a level little lower than a top edge face of the screen 2 so that the rings 4 and the connecting fitting 5 will not constitute obstacles when projection image units A are piled up in the vertical direction and a clearance will not be present between the upper and lower edge faces of the screen 2. The projection image units A are assembled as shown in FIG. 25, but an angle of visibility for the screen 2 is limited, and when piled up in multiple stages, sometimes images on screens 2 in upper stages may be hardly seen by a viewer near the screen 2. To solve this problem, the projection image units A in upper stages are inclined so that the entire screen will be curved, as shown in FIG. 27. In this case, a spacer 9 is used between the upper and lower projection image units A. Note that examples of disclosure of conventional projection image units A are included in Japanese Laid-Open Patent Publication 1-228281 (U.S. Pat. No. 4,903,137)
One of the problems concerning the conventional projection image units A as described above is, however, that the construction and strength thereof are inadequate to form a large screen.
In other words, weight of a single projection image unit A is about 100 kg in case of heavier ones, although the weight depends on size of the screen 2. Although reduction of weight is desirable when easiness of handling is taken into account, a degree of strength is required to expand an area of the screen, which means that there is a limit in reduction of the weight. On the other hand, in order to form a large screen for such devices as high resolution televisions, demands for which have been increasing year by year, more and more projection image units A must be piled up in every direction, but in this configuration, total weight of projection image units A in upper stages is loaded to those in lower stages, and compressive load which a single projection image unit A can endure goes near the limit, resulting in the restriction for forming a large screen.